@William K. I like your enthusiasm for lower tech solutions than microcontrollers, philosophically, at least. We could even build a calculator with TTL chips or discreet transistors. Realistically, though, parts count and board space start to lose out on zero parts and space for software. And let's face it, I don't know how to build a transistor so it's all technical beyond primitivism. Now we have devices like PSoC (Programmable System on a Chip) that can combine anything we need -- PWM controllers, video processing, capacitance sensing, multiplexing. And programming is just a matter of using a screen menu with the PSoCCreator.

I understand your DIY drive. From my handle you can guess that I play 78RPM records going back to 1895 but it takes a 5' x 15' closet to house 16,000 songs. It's sad that people don't get the joy I get from that but the iPod won.

I'm certain that I could have designed the circuit without a microcontroller if I had wanted to, but I felt that this approach would arrive at a working design more quickly and cheaply. Besides, a cheap microcontroller and a little bit of software can replace a lot of discreet electronics. For that reason, almost everything uses a microcontroller nowadays. Even my toaster and my toothbrush have microcontrollers in them. The PIC microcontroller I used in the transmitter unit costs about the same as a 555 timer you might use in a hardware gap detector, but requires no resistors and capacitors. It also performs the 1.5 second timer function and the encoding for the radio link.

If you want to spend the time designing a non-microcontroller version of my gadget, go for it. Once you come up with a circuit, please send me a copy of it. My email address is in the article.

Armorris, I guess it comes with "point of view", since I can visualize the circuit fo gap detection as not that complex. And the main focus of this project is a useful device, not as an electronics learning tool. And I was not even thinking about the radio link part of the project when I made those comments.

Now I need to spend some time and figure just exactly how it would be done as an analog-digital mix, but without any processer. Talk is cheap, about 4 cents a pound. Now I need to see if I can provide a similar function in analog.

Yes, you're right. It probably would not be much more complex to do the gap detection and timing with analog or discreet digital circuits, but this was easier. Also, unless you buy a remote system with a built-in encoder/decoder, you would still need a microcontroller to generate the digital code for it. The simple analog encoding systems I grew up with are not adequate these days. The Chinese company I bought the radio link from has 4-channel remote systems with built-in encoder/decoders. It seems like such a waste for this application, however.

I certainly have the electronic design skill to do it, had I chosen to do so. Changing the software in the PIC is FAR easier than rewiring the hardware if design changes are needed. If the PIC is programmed in a production programmer, it is guaranteed by Microchip to hold its program for 40 years.

This is an interesting device, and a unique application. Possibly the use of the PIC processor made the design easier, but it could also have been done in the analog realm, with a small amount of digital glue logic. That would remove the requirement for programming from the construction, and make the design available for many years, and to a much broader range of people. Yes, a bit more electronic design skill would possibly be needed, but the design would also have been simpler to adjust to changing needs.

That is an excellent question. I know nothing about the requirements for medical electronics. I'm certain though, that the gadget could be modified to meet those requirements.

The mute button only prevents the receiver from being activated for 10 minutes, or until it's unmuted. It doesn't have any effect on privacy. The device has been designed so that people talking in the patient's room will not trigger it unless they are close to the microphone and make a continuous sound for 1.5 seconds.

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